电沉积钯钴合金形貌及其耐蚀行为研究

Morphology and Anticorrosion Behavior of Electrodeposited Pd-Co Alloys

为更好地了解Pd-Co合金的材料特性,采用电沉积法制备了Pd-Co合金镀层,通过扫描电镜(SEM)和动电位扫描(Tafel)对Pd-Co合金镀层的表面形貌和耐蚀性进行了考察。结果表明,Pd-Co合金镀层的晶粒尺寸和表面形貌受镀液中Co2+浓度和电流密度的影响较大,随着镀液中Co2+浓度的增加,镀层的晶粒尺寸逐渐减小,晶粒从片状变为球状;随着电流密度的增大,Pd-Co合金镀层的晶粒从粒状变为块状,晶粒尺寸呈先减小后增大的趋势。当电流密度小于1.0A/dm2时,Pd-Co共沉积过程受阴极极化控制;当电流密度大于1.0A/dm2时,其沉积过程受浓差极化控制。Pd-Co合金镀层的耐蚀性按腐蚀介质为中性、酸性、碱性的顺序逐步降低。

Pd-Co alloy deposits were prepared by electrodeposition. For better understanding their properties, the surface morphology and corrosion resistance of the Pd-Co alloys were investigated by SEM and potentiodynamic polarization techniques. The results showed that the grain size and morphology at the Pd-Co alloy was influenced greatly by Co2+ concentration and current density. With the increase of Co2+ concentration, the grain size of this alloy decreased gradually and its morphology varied from sheet to rotundity; with increasing of current density, the surface morphology of this alloy varied from granule shape to nubby, and the grain size decreased firstly and then increased. When the current density is smaller than 1.0 A/dm2, the co-deposition of Pd-Co alloy was controlled by cathodic polarization. As the current density was increased greater than 1.0 A/dm2, its co-deposition behavior was dominated by concentration difference polarization. The corrosion resistance of this deposit decreased according to the sequence of neutral, acidic and alkaline corrosion electrolytes.